The present invention relates to system for safely supplying pressurized mixed concrete from a concrete pump to a supply line that typically is lengthy—with the system having a recirculation capability for diverting at least a selected portion of a flow of pressurized concrete about to enter a supply line back to an open-to-atmosphere reservoir from which the concrete pump draws concrete—so that supply line pressure can be regulated, diminished, relieved or jogged if need be when a clog, blockage or other supply line concern is noted. The system provides a safe way to relieve supply line pressure and to deal with supply line concerns without any need to waste valuable mixed concrete by discharging it into the environment, and without having to dangerously open a highly pressurized supply line connection.
Vehicles often called “concrete trucks” are used to deliver mixed concrete to the vicinity of a work site where the mixed concrete is to be poured so structures such as foundations, footings, floors, slabs and the like can be formed. Pumping equipment carried on trailers or on self-propelled vehicles often called “pumpers” deliver pressurized flows of concrete from hoppers (supplied with concrete by concrete trucks) through typically lengthy supply lines that duct the pressurized flows to specific work site locations where skilled concrete workers move the flexible hoses from place to place to control how and where concrete is poured.
The lengthy supply lines may extend vertically as well as horizontally. Sometimes the supply lines even bridge over the roof of a house, and often the supply lines are tasked to reach to the upper floors of high-rise buildings. The workers who direct the flows of concrete from the delivery ends of supply line hoses typically communicate by radio or by portable phone with pumper vehicle personnel who control the supply of pressurized mixed concrete to the supply lines.
When a clog, blockage or other supply line concern is detected, one prior art proposal calls for a so-called “discharge valve” or “pressure relief valve” to be manually opened to the environment. This causes an immediate and forceful discharge of pressurized concrete that is not only ridiculously wasteful of mixed, ready-to-pour concrete, but also creates a considerable mess that needs to be cleaned up before the concrete sets. More importantly, manually opening a discharge valve to empty the contents of a high pressure supply line can seriously endanger personnel who are working in the vicinity of where the valve has been opened.
Sometimes the pumper operator is the person who must take on the unpleasant task of standing adjacent the pressurized supply line while he struggles to manually turn a threaded T-handle through the many revolutions needed to fully open the discharge valve. This can subject the operator to a nasty splatter of gritty concrete, and can sometimes cause the operator to be pelted with rapidly discharging aggregate while concrete flung by spats of pressure piles up about his shoes or boots. During this discharge of concrete, the operator must continue to inquire, by radio or telephone, whether the wasteful discharge of concrete must continue or can be terminated. When word is received that the wasteful discharge of concrete is to stop, the valve member (that was opened with some difficulty), now must be closed—even though the valve member is now laden with, if not completely buried in, concrete that continues to discharge, but at a slower pace—and must be wiped clean enough to be moved back into some semblance of closure with the supply line opening that previously had been sealed by the valve member.
Before the notion of providing the supply line of a concrete pumper with a so-called “drain valve” was conceived, the approach that previously had been taken to relieve supply line blockages was to open one of the many pipe-to-pipe or pipe-to-hose connections that are present in a lengthy supply line. Usually the connection that is quickly selected to be opened is at a distance spaced from the pumper vehicle so that any resulting powerful discharges of pressurized concrete from an opened connection will not coat the pumper vehicle, or other vehicles that hopefully are parked sufficiently far away from the opened connection to avoid being damaged.
Opening a connection in a highly pressurized supply line filled with concrete presents a more serious and dangerous problem than construction workers (who may rush to assist) can be expected to anticipate. The sudden discharge of pressurized concrete from an opened supply line connection is almost always a violent event not to be forgotten. It is the sort of event that can, and often does, cause lengthy sections of supply line pipe filled with heavy concrete to jump and thud about like angry battering rams, while the lighter-weight connector clamps that have been released when connections are opened are sometimes launched wildly into the air, sometimes impacting vehicles parked a reasonable distance from the pumper, or personnel who may be standing by, more closely.
Sprays of concrete from the just-opened connections of pressurized supply lines are have been known to splatter and coat trees, other plants, sidewalks, construction equipment—and, sometimes the nicely painted and finished surfaces of recently built structures. The the clean-up of whatever kind of sometimes enormous mess that may have been may have resulted from the opening of even one pressurized supply line connection sometimes has to wait while injured personnel are attended.
If a supply line connection has been opened in an effort to find and relieve a clog or blockage, it is essential to keep in mind that the supply line pipes and hoses must be put back into service as quickly as possible—or must be cleared quickly of ready-to-set concrete, for, if the ready-to-set concrete is stagnantly retained in supply line pipes and hoses for any appreciable length of time, the concrete will set in almost no time at all as the supply lines bake in the afternoon sun. Time passes rapidly at job sites where urgent attention is being paid to matters that must be addressed without delay—and, concrete-filled supply line pipes and hoses baking quietly in the sun are easy to detrimentally ignore.
A shortcoming of all prior proposals for dealing with supply line clogs and blockages has been that no effective method or means has been developed or offered that permits supply line pressure to be cycled or jogged up and down—even though rapid changes in supply line pressure are known to sometimes be of help in quickly relieving or breaking up clogs and blockages. Trying to turn concrete pumps off and on has not proved to provide an effective way to rapidly modify supply line pressure in a manner that is useful in dealing with clogs and blockages. A better approach has long been needed.
Likewise, no method or means has been forthcoming for sensibly salvaging the ready-to-set concrete that has been cleared from supply line pipes and hoses. Although avoiding supply line clogs and blockages has always been an objective during use of a concrete pumper, no one knows precisely how to accomplish this laudable objective in a reliable and foolproof manner.